SEOUL, July 9 : Demand for SK Hynix's $28 billion U.S. share sale was more than seven times available shares, a person familiar with the matter said, underscoring huge investor appetite for one of the most important companies in the AI supply chain.The offering from the South Korean chipmaker, which will finance new factories and equipment to meet surging AI chip demand, is set to be the world's second-biggest share sale after SpaceX's record-breaking $85.7 billion IPO last month.SK Hynix declined to comment. The person declined to be identified as details of the share sale were confidential. Shares in SK Hynix jumped 6 per cent in morning trade. Underwriters have told investors that pricing guidance is expected to come after the South Korean stock market closes on Thursday with allocation